The backlights

Now it was time to work at the back. I didn't created the back lights with the half of the mesh, because I didn't saw correctly the influence of the changes I made to the mesh. Now with all the mesh, I was able to make changes, to apply mesh smooth and see how it looks.
Like in front with the smaller headlights, here I chamfer two edges, then extruded the faces:

Then It came the second pair of headlights (see in the pictures how I deleted some face then created them again with different diagonal):

I sliced the middle faces between the backlights to create some room for the registration number:

After that I started to work with the tail wing, I sliced some faces, then I selected some thin faces from the back:

Next I extruded the faces twice:

This is how the tail looked:

In the next 3 images you'll se how I made the back holes (with slice, extrude). You notice that I applied the slice
modifier several times to cut some faces. I also deleted some polygons and then recreated them with the different diagonal.
After one step I always previewed with mesh smooth to see if everything was OK:

Next: the trunk (or what it's called I have no clue sorry:)

Same way I sliced the faces to make some room for the holes, then at first I wanted to separate this part of the mesh from the rest of the car but finally I decided it was best to make everything in one mesh (in the end I hidden the rest of the car to have better control of the faces I was working on):

And finally I sliced twice the middle part and then I selected the faces and extruded them: